The general acceptance of industry automation as a central requirement for improving productivity has increased the acceptance level of the robot or manipulator apparatus as a mechanism for achieving automated industrial applications. The acceptance of robots as a useful, industrial "tool" has resulted in a market demand for robot systems exhibiting simplified design characteristics of a machine tool suitable for control by a conventional computer numerical control, direct numerical control and off-line programming with languages such as an Automatic Programming Tool (APT).
High powered lasers are ideally suited to be used as a source of heat in various material processing applications which include the vaporization of materials, drilling and cutting operations. Lasers are also applicable to procedures, such as welding or surface cladding of materials, that it to say, processes and procedures which require the melting of materials. Also, the temperature of solid phase materials can be varied by the use of the laser in hardening and annealing operations.
The thermal effects which are experienced by materials when exposed to the laser beam are primarily dependent upon the intensity of the laser energy, the absorptivity of the material, and the length of time during which the material is exposed to the laser beam. Precise control over these parameters determines the resulting change in the phase or the state of the material. Usually, when lasers are used in processes such as welding, cutting and surface treatment, the area of the workpiece to be processed is oriented in such a way that is it nearly normal to the laser beam with the beam impinging squarely on the workpiece surface. This configuration optimizes the absorptivity of the material and facilitates its heating. Generally, the laser and the workpiece are caused to move relative to each other. This relative motion can be accomplished in two ways. First, the beam can be traversed over a stationary workpiece. Second, the workpiece can be manipulated under a fixed laser beam. Typically, the former method requires that the laser beam be moved either by mounting the laser on a movable device or by directing the beam from the fixed laser to the workpiece by use of a movable optical system.
A dedicated effort has been directed to the optimization of the use of industrial manipulators and high powered lasers to provide an integrated laser robot system. U.S. patent application Ser. No. 485,076, entitled "General Purpose Orthogonal Axes Manipulator System" by Daniel P. Soroka et al., which is assigned to the assignee of the present invention, discloses an overhead gantry style robot with a large rectangular working envelope. This robot permits programming in Cartesian coordinates as contrasted with the more complicated polar coordinates. This gantry robot design provides a rigid manipulator that supports machine tool-type interpolation moves, high accuracy and repeatability while permitting robotic-type velocity and dexterity. The gantry design provides for an overhead X axis assembly supported by vertical structural members. The Y axis assembly extends as an arm from the X axis assembly and further supports a vertical Z axis assembly. In addition to the orthogonal X, Y and Z axis assemblies, a mounting surface on the Z axis assembly is designed to accommodate a multiple axis rotary wrist to which an appropriate end effector can be attached. It is to this end effector that the present invention is more specifically directed as will be seen below.
Allowed U.S. patent application Ser. No. 460,346, which is entitled "Robotic Laser Beam Delivery Apparatus" by Daniel J. Plankenhorn, which application is assigned to the assignee of the present invention, discloses a light beam directing apparatus which permits a reflected beam of light such as a laser, to be directed in a path which comprises a plurality of straight segments. Each segment of the beam is associated with a segment of a robot's axis in a fixed spatial relationship. The aforedescribed patent applications describe only a portion of a total system which can be utilized to provide a complete work cell.
A significant advantage of a system as described above which incorporates a robot and a laser resides in the fact that the same machine can accomplish drilling, cutting, welding, surfacing, alloying/cladding, hardening and annealing with only a "tool" change of the focussing optics and a programming adjustment of beam power and exposure time. The ultimate system for use in such material processing would include all tooling changes in software control thus using the full versatility of the laser and robot system. Unfortunately, a problem resides in the fact that the changing of the focussing optics to obtain different focal lengths, spot sizes, intensities and etc. is a manual operation.
It is, therefore, an object of this invention to eliminate the manual operation of changing end-of-arm tooling by locating different sets of "tooling" on a carousel at the end of the robot's arm and manipulating this carousel and the tooling located thereon through the use of servo-control from the robot control.
It is a further object of this invention to provide end-of-arm tooling which provides two or more end effectors which can be automatically controlled through the robot or system controller.
It is a further object of this invention to provide an end effector which through a solenoid actuated mechanism which couples in a light leak-proof fashion, automatically to the beam conveyance system which delivers the laser beam from the laser to the workpiece.
It is a futher object of this invention to provide one or more end effectors disposed in a carousel relationship for automatic movement and control by the robot or system controller.
It is yet again another object of this invention to provide a carousel system for use in combination with a generic shield for a variety of material processes.